Interbody device insertion systems and methods

ABSTRACT

Provided is a system for implanting an interbody device into a disc space located between a first and second vertebra includes a guide frame including a guide member having an opening. The system further includes an implant trial including an elongated body and a base plate coupled to the elongated body. The elongated body of the implant trial is releasably coupled to the guide member of the guide frame during use such that the opening guides longitudinal movement of the implant trial relative to the guide frame. The system still further includes a dilator operatively coupled to the elongated body during use for distracting the disc space. The system still further includes an insertion instrument including an elongated body and an insertion member coupled to the elongated body. The elongated body of the insertion instrument is releasably coupled to the guide member of the guide frame during use such that the opening guides longitudinal movement of the insertion instrument relative to the guide frame. The insertion member is releasably coupled to at least a portion of the interbody device during use.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.13/072,511 entitled “INTERBODY DEVICE INSERTION SYSTEMS AND METHODS”filed on Mar. 25, 2011, which is incorporated by reference herein.

BACKGROUND

1. Field of the Invention

Embodiments of the invention generally relate to functional spinalimplant assemblies for insertion into an intervertebral space betweenadjacent vertebrae of a human spine. More specifically, embodimentsrelate to methods of using and installing interbody devices.

2. Description of Related Art

The human spine is a complex mechanical structure including alternatingbony vertebrae and fibrocartilaginous discs that are connected by strongligaments and supported by musculature that extends from the skull tothe pelvis and provides axial support to the body. The intervertebraldiscs provide mechanical cushion between adjacent vertebral segments ofthe spinal column and generally include two basic components: thenucleus pulposus and the annulus fibrosis. The intervertebral discs arepositioned between two vertebral end plates. The annulus fibrosis formsthe perimeter of the disc and is a tough outer ring that binds adjacentvertebrae together. The end plates are made of thin cartilage overlyinga thin layer of hard cortical bone that attaches to the spongy,cancellous bone of a vertebra. The vertebrae generally include avertebral foramen bounded by the anterior vertebral body and the neuralarch, which consists of two pedicles that are united posteriorly by thelaminae. The spinous and transverse processes protrude from the neuralarch. The superior and inferior articular facets lie at the root of thetransverse process.

The spine is a flexible structure capable of a high degree of curvatureand twist in nearly every direction. The motion segment or functionalspinal unit (FSU) is the basic motion unit of the lumbar spine. Theanterior elements of the FSU include the vertebral bodies, theintervertebral disc, and the connecting soft tissues and ligaments. Theposterior elements of the FSU include the bony ring created by thepedicles and lamina, the facet joints, and the connecting soft tissuesand ligaments. The facet joints are located on both sides at thejunction of superior and inferior bony projections of the posteriorelements.

The total motion of the spine results from the cumulative motion of theindividual FSUs. Each motion segment allows rotational motion in threedirections (flexion-extension, lateral bending, and axial rotation) andtranslational motion in three directions (anterior-posterior,medial-lateral, and superior-inferior). The available motion isprimarily governed by the intervertebral disc, facet joints, andligaments. Typical maximum amounts of lumbar rotation are up to about17° of flexion-extension, 6° of lateral bending, and 3° of axialrotation. Moderate motions of the spine during everyday living mayresult in less than 10° of flexion-extension.

Translation of one vertebral body with respect to an adjacent vertebralbody can be up to a few millimeters during rotation. The quality of themotion is described by the shape of the motion segment moment-rotationcurve. The motion segment moment-rotation curve is the rotationalresponse of the FSU due to loading away from the center of rotation. Themoment-rotation curves are non-linear with an initial low stiffnessregion, followed by a higher stiffness region. The initial region ofhigh flexibility, where spinal motion is produced with less resistanceto bending moments, is typically referred to as the neutral zone.Typically, the neutral zone ranges from 10-50% of the total range ofmotion. The stiffness (Nm/deg) in the neutral zone is about 10-30% ofthe high stiffness region. Alterations to the FSU caused by surgicalintervention, degeneration, acute injury, or other factors are thoughtto change this non-linear behavior.

Genetic or developmental irregularities, trauma, chronic stress, anddegenerative wear can result in spinal pathologies for which surgicalintervention may be necessary. In cases of deterioration, disease, orinjury, an intervertebral disc, or a portion of the intervertebral disc,may be removed from the human spine during a discectomy.

After some discectomies, one or more non-dynamic intervertebral devicesmay be placed in the disc space to fuse or promote fusion of theadjacent vertebrae. During some procedures, fusion may be combined withposterior fixation to address intervertebral disc and/or facet problems.The fusion procedure (e.g., posterior lumbar interbody fusion) and theposterior fixation procedure may be performed using a posteriorapproach. The posterior fixation and non-dynamic intervertebral devicesmay cooperate to inhibit motion and promote bone healing. Fusing twovertebrae together results in some loss of motion. Fusing two vertebraetogether may also result in the placement of additional stress on one ormore adjacent functional spinal units. The additional stress may causedeterioration of an adjacent functional spinal unit that may result inthe need for an additional surgical procedure or procedures.

After some discectomies, a dynamic intervertebral device (DID) may beplaced in the disc space. The DID may allow for movement of adjacentvertebrae coupled to the DID relative to each other. U.S. Pat. No.4,863,477 to Monson, which is incorporated herein by reference,discloses a resilient dynamic device intended to replace the resilienceof a natural human spinal disc. U.S. Pat. No. 5,192,326 to Bao et al.,which is incorporated herein by reference, describes a prostheticnucleus for replacing just the nucleus portion of a human spinal disc.U.S. Patent Application Publication No. 2005/0021144 to Malberg et al.,which is incorporated herein by reference, describes an expandablespinal implant. Allowing for movement of the vertebrae coupled to thedisc prosthesis may promote the distribution of stress that reduces oreliminates the deterioration of adjacent functional spinal units.

An intervertebral device may be positioned between vertebrae using aposterior approach, an anterior approach, a lateral approach, or othertype of approach. A challenge of positioning a device between adjacentvertebrae using a posterior approach is that a device large enough tocontact the end plates and slightly expand the space must be insertedthrough a limited space. This challenge is often further heightened bythe presence of posterior osteophytes, which may cause “fish mouthing”of the posterior vertebral end plates and result in very limited accessto the disc. A further challenge in degenerative disc spaces is thetendency of the disc space to assume a lenticular shape, which mayrequire a larger implant than can be easily introduced without causingtrauma to adjacent nerve roots. The size of rigid devices that maysafely be introduced into the disc space is thereby limited. During somespinal fusion procedures using a posterior approach, two implants areinserted between the vertebrae. During some posterior procedures, one orboth facet joints between the vertebrae may be removed to provideadditional room for the insertion of a fusion device. Removal of thefacet may also allow for the removal of soft tissue surrounding thefacet (for example, the facet capsule) that work to resist posteriordistraction.

The anterior approach poses significant challenges as well. Though thesurgeon may gain very wide access to the interbody space from theanterior approach, this approach has its own set of complications andlimitations. The retroperitoneal approach usually requires theassistance of a surgeon skilled in dealing with the visceral contentsand the great vessels. The spine surgeon has limited access to the nerveroots and little or no ability to access or replace the facet joints.Complications of the anterior approach that are approach specificinclude retrograde ejaculation, ureteral injury, and great vesselinjury. Injury to the great vessels may result in massive blood loss,postoperative venous stasis, limb loss, or death. The anterior approachis often more difficult in patients with significant obesity and may bevirtually impossible in the face of previous retroperitoneal surgery.

Despite the difficulties of the anterior approach, the anterior approachdoes allow for the wide exposure needed to place a large device. Inaccessing the spine anteriorly, one of the major structural ligaments,the anterior longitudinal ligament, must be completely divided. A largeamount of anterior annulus must also be removed along with the entirenucleus. Once these structures have been resected, the vertebral bodiesmay need to be over distracted to place the device within the disc spaceand restore disc space height. Failure to adequately tension theposterior annulus and ligaments increases the risk of device failureand/or migration. Yet in the process of placing these devices, theligaments are overstretched while the devices are forced into the discspace under tension. Over distraction can damage the ligaments and thenerve roots. The anterior disc replacement devices currently availableor in clinical trials may be too large to be placed posteriorly, and mayrequire over distraction during insertion to allow the ligaments to holdthem in position.

A facet joint or facet joints of a functional spinal unit may besubjected to deterioration, disease or trauma that requires surgicalintervention. Disc degeneration is often coupled with facetdegeneration, so that disc replacement only may not be sufficienttreatment for a large group of patients.

Facet degeneration may be addressed using a posterior approach. Thus asecond surgical approach may be required if the disc degeneration istreated using an anterior approach. The need to address facetdegeneration has led to the development of facet replacement devices.Some facet replacement devices are shown in U.S. Pat. No. 6,419,703 toFallin et al.; U.S. Pat. No. 6,902,580 to Fallin et al.; U.S. Pat. No.6,610,091 to Reiley; U.S. Pat. No. 6,811,567 to Reiley; and U.S. Pat.No. 6,974,478 to Reiley et al, each of which is incorporated herein byreference. The facet replacement devices may be used in conjunction withanterior disc replacement devices, but the facet replacement devices areusually not designed to provide a common center of rotation with theanterior disc replacement devices. The use of an anterior discreplacement device that has a fixed center of rotation contrary to thefixed center of rotation of the facet replacement device may restrict ordiminish motion and be counterproductive to the intent of the operation.

During some spinal stabilization procedures a posterior fixation systemmay be coupled to the spine. During some procedures, posterior fixationsystems may be coupled to each side of the spine. The posterior fixationsystems may include elongated members that are coupled to vertebrae byfasteners (e.g., hooks and screws). One or more transverse connectorsmay be connected to the posterior fixation systems to join and stabilizethe posterior fixation systems.

During some spinal stabilization procedures, dynamic posteriorstabilization systems may be used. U.S. Patent Publication Nos.2005/0182409 to Callahan et al.; 2005/0245930 to Timm et al.; and2006/0009768 to Ritland, each of which is incorporated herein byreference, disclose dynamic posterior stabilization systems.

During some spinal stabilization procedures, a dynamic interbody deviceor devices may be used in conjunction with one or more dynamic posteriorstabilization systems. U.S. Patent Publication No. 2006/0247779 toGordon et al., U.S. Patent Publication No. 2008/0234740 to Landry etal., and U.S. Patent Publication No. 2009/0105829 to Gimbel et al. eachof which is incorporated herein by reference, disclose dynamic interbodydevices and dynamic posterior stabilization systems that may be usedtogether to stabilize a portion of a spine.

Unfortunately, in the above described techniques, it may be difficult toprepare an intevertabral disc space for receipt of one or more spinalimplants and it may also be difficult to accurately place the implantsand devices described above within the disc space. For example, whenplacing a dynamic interbody device into the disc space it may berequired that the device is positioned precisely relative to theadjacent vertebra to provide for effective operation of the implantdevices during use. Moreover, in some instances where multiple dynamicinterbody devices are placed within the disc space, it may be requiredthat the devices are positioned precisely relative to one another toprovide for effective operation of the implant devices during use.Furthermore, improper placement of devices may increase the risk ofinjury to the patient, including nerve root damage during disc spacepreparation and interbody device placement.

SUMMARY

Various embodiments of interbody devices and insertion methods forinstalling interbody devices are described. In some embodiments,provided is a method of implanting an interbody device into a disc spacelocated between a first and second vertebra including inserting a baseplate of a first implant trial into the disc space. The method furtherincludes inserting a base plate of a second implant trial into the discspace, wherein the second implant trial is coupled to the first implanttrial to position the base plate of the first implant trial relative tothe base plate of the second implant trial. The method still furtherincludes inserting one or more dilators into the disc space proximatethe base plates of the first or second implant trials to distract thefirst and second vertebrae. The method still further includes removingthe base plate of the first implant trial and the dilators from the discspace. The method still further includes inserting the interbody deviceinto the disc space in substantially the same position as the base plateof the first implant trial.

In some embodiments, provided is a method of implanting interbodydevices into a disc space located between a first and second vertebraincluding inserting a base plate of a first implant trial to a selectedlocation at least partially within the disc space, the first implanttrial including an elongated body and a base plate coupled to theelongated body. The selected location includes a selected angle withrespect to the sagittal plane of the vertebra. The method furtherincludes inserting a first dilator between the base plate of the firstimplant trial and the first or second vertebra to distract thevertebrae. The method still further includes coupling a first guidemember of a guide frame to the elongated body of the first implanttrial, the guide frame further including a second guide member. Thefirst and second guide members of the guide frame are rigidly coupledand positioned at a selected convergent angle relative to one another.The method still further includes coupling an elongated body of a secondimplant trial to the second guide member such that a base plate of thesecond implant trial is inserted at least partially within the discspace, and such that at least a portion of the base plate of the secondimplant trial abuts a portion of the base plate of the first implanttrial. The method still further includes inserting a second dilatorbetween the base plate of the second implant trial and the first orsecond vertebra to distract the vertebrae. The method still furtherincludes removing the base plate of the first implant trial and thefirst dilator from the disc space and uncoupling the elongated body ofthe first implant trial from the first guide member. The method stillfurther includes, coupling an elongated body of a first insertioninstrument to the first guide member such that a first interbody deviceis inserted at least partially within the disc space in substantiallythe same position as the base plate of the first implant trial, thefirst insertion instrument including the elongated body and an insertionmember coupled to the elongated body, wherein the insertion member isreleasably coupled to the first interbody device. The first interbodydevice is positioned within the disc space at a selected angle withrespect to the sagittal plane of the vertebra. The method still furtherincludes, removing the base plate of the second implant trial and thesecond dilator from the disc space and uncoupling the elongated body ofthe second implant trial from the second guide member. The method stillfurther includes, coupling an elongated body of a second insertioninstrument to the second guide member such that a second interbodydevice is inserted at least partially within the disc space insubstantially the same position as the base plate of the second implanttrial, the second insertion instrument including an elongated body andan insertion member coupled to the elongated body, wherein the insertionmember is releasably coupled to the second interbody device. At least aportion of the second interbody device is located at or near the firstinterbody device. The method still further includes, uncoupling thefirst interbody device from the insertion member of the first insertioninstrument. The method still further includes, uncoupling the secondinterbody device from the insertion member of the second insertioninstrument.

In some embodiments, provided is a system for implanting an interbodydevice into a disc space located between a first and second vertebraincluding a guide frame, the guide frame including a guide member havingan opening. The system further includes an implant trial including anelongated body and a base plate coupled to the elongated body. Theelongated body of the implant trial is releasably coupled to the guidemember of the guide frame during use such that the opening guideslongitudinal movement of the implant trial relative to the guide frame.The system still further includes a dilator operatively coupled to theelongated body during use for distracting the disc space. The systemstill further includes an insertion instrument including an elongatedbody and an insertion member coupled to the elongated body. Theelongated body of the insertion instrument is releasably coupled to theguide member of the guide frame during use such that the opening guideslongitudinal movement of the insertion instrument relative to the guideframe. The insertion member is releasably coupled to at least a portionof the interbody device during use.

In some embodiments, provided is a system for implanting interbodydevices into a disc space located between a first and second vertebraincluding a guide frame, the guide frame including a first guide memberhaving a first opening and a second guide member have a second opening.The system further includes first and second implant trials eachincluding an elongated body and a base plate coupled to the elongatedbody. The elongated bodies of the first and second implant trials arereleasably coupled to the first and second guide members of the guideframe respectively during use such that the openings of the first andsecond guide members of the guide frame guide longitudinal movement ofthe first and second implant trials respectively relative to the guideframe. The system still further includes a dilator operatively coupledto the elongated body of the first or second implant trial during usefor distracting the disc space. The system still further includes, firstand second insertion instruments each including an elongated body and aninsertion member coupled to the elongated body. The elongated bodies ofthe first and second insertion instruments are releasably coupled to thefirst and second guide members of the guide frame respectively duringuse such that the openings of the first and second guide members of theguide frame guide longitudinal movement of the first and secondinsertion instruments respectively relative to the guide frame. Theinsertion members of the first and second insertion instruments are eachreleasably coupled to complementary interbody devices during use.

In some embodiments, provided is a system for implanting an interbodydevice into a disc space located between a first and second vertebra,including a guide frame, the guide frame including an insertion bridgeand first and second guide members. The first and second guide membersof the guide frame are rigidly coupled to the insertion bridge andpositioned at a convergent angle relative to one another during use. Thefirst and second guide members of the guide frame each include anopening, the openings including a channel with a lateral opening. Thefirst and second guide members of the guide frame each include at leasta first portion of a locking mechanism. The system further includesfirst and second implant trials each including an elongated body and abase plate coupled to the elongated body. The elongated bodies of thefirst and second implant trials are releasably coupled to the first andsecond guide members of the guide frame respectively during use suchthat the respective openings of the first and second guide members ofthe guide frame guide longitudinal movement of the implant trialsrelative to the guide frame. The system still further includes, adilator operatively coupled to the elongated body of the first or secondimplant trial during use for distracting the disc space. The systemstill further includes, first and second insertion instruments eachincluding an elongated body and an insertion member coupled to theelongated body. The elongated bodies of the first and second insertioninstruments are releasably coupled to the first and second guide membersof the guide frame respectively during use. The insertion members of thefirst and second insertion instruments are releasably coupled tocomplementary interbody devices during use.

In some embodiments, provided is a system for implanting interbodydevices into a disc space located between a first and second vertebraincluding a guide frame, the guide frame including first and secondguide members. The first and second guide members of the guide frame arerigidly coupled to one another and positioned at a selected convergentangle relative to one another during use. The first and second guidemembers of the guide frame each include openings receiving an elongatedbody during use. The first and second guide members of the guide frameeach include at least a first portion of a locking mechanism fixedlycoupling the guide frame to an elongated body during use. The systemfurther includes first and second implant trials each including anelongated body and a base plate coupled to the elongated body. Theelongated bodies of the first and second implant trials are releasablycoupled to the first and second guide members of the guide framerespectively during use such that the respective openings guidelongitudinal movement of the implant trials relative to the guide frame.The elongated bodies are configured to advance laterally into engagementwith the openings of the first and second guide members of the guideframe. The system further includes first and second insertioninstruments each including an elongated body and an insertion membercoupled to the elongated body. The elongated bodies of the first andsecond insertion instruments are releasably coupled to the first andsecond guide members of the guide frame respectively during use. Theinsertion members of the first and second insertion instruments arereleasably coupled to complementary interbody devices during use.

In some embodiments, provided is a system for implanting interbodydevices into a disc space located between a first and second vertebraincluding a guide frame, the guide frame including first and secondguide members. The system further includes first and second implanttrials, the first and second implant trials each including an elongatedbody. The elongated bodies of the first and second implant trials arereleasably coupled to the first and second guide members of the guideframe respectively during use. The first and second implant trials eachfurther include a base plate coupled to the elongated body. The baseplate includes an inferior and/or superior surface having a shape thatis substantially the same as the shape of an inferior and/or superiorsurface of an interbody device. The system still further includes adilator releasably coupled to the elongated body of the first or secondimplant trial during use such that, the dilator can be uncoupled fromthe elongated body and replaced with another dilator. The system stillfurther includes first and second insertion instruments each includingan elongated body and an insertion member coupled to the elongated body.The elongated bodies of the first and second insertion instruments arereleasably coupled to the first and second guide members of the guideframe respectively during use. The insertion members of the first andsecond insertion instruments are releasably coupled to complementaryinterbody devices during use.

In some embodiments, provided is a system for implanting interbodydevices into a disc space located between a first and second vertebraincluding a guide frame including first and second guide members. Thefirst and second guide members of the guide frame are rigidly coupled toone another and positioned at a selected convergent angle relative toone another during use. The system further includes first and secondimplant trials each including an elongated body and a base plate coupledto the elongated body. The elongated bodies of the first and secondimplant trials are releasably coupled to the first and second guidemembers of the guide frame respectively during use. The system stillfurther includes first and second dilators releasably coupled to therespective elongated bodies of the first and second implant trialsduring use such that the first and second dilators can be uncoupled fromthe elongated bodies of the first and second implant trials and replacedwith another dilator. The base plates of the first and second implanttrials are coupled to the respective elongated bodies of the first andsecond implant trials such that, during use, when the elongated bodiesof the first and second implant trials are coupled to the respectivefirst and second guide members of the guide frame, and when the baseplates of the first and second implant trials are at least partiallyinserted into the disc space, the base plates of the first and secondimplant trials are positioned at a substantially equalanterior-posterior depth within the disc space. The system still furtherincludes first and second insertion instruments each including anelongated body and an insertion member coupled to the elongated body.The elongated bodies of the first and second insertion instruments arereleasably coupled to the first and second guide members of the guideframe respectively during use. The insertion members of the first andsecond insertion instruments are releasably coupled to complementaryinterbody devices during use.

In some embodiments, provided is a system for implanting interbodydevices into a disc space located between a first and second vertebraincluding a guide frame, the guide frame including an insertion bridgeand first and second guide members. The first and second guide membersof the guide frame are rigidly coupled to the insertion bridge andpositioned at a selected convergent angle relative to one another duringuse. The first and second guide members of the guide frame each includean opening, the openings including a channel with a lateral opening. Thefirst and second guide members of the guide frame each include a firstportion of a locking mechanism. The system further includes first andsecond implant trials including an elongated body and a base platecoupled to the elongated body. The elongated body of the first implanttrial is slidable through the opening of the first guide member and theelongated body of the second implant trial is slidable through theopening of the second guide member. The elongated bodies of the firstand second implant trials each include a second portion of the lockingmechanism, such that, during use, when the first and second portions ofthe locking mechanism are engaged, the first and second guide members ofthe guide frame are fixedly coupled to the respective elongated bodiesof the first and second implant trials at a selected location on theelongated bodies of the first and second implant trials. The first andsecond implant trials each include a longitudinal slot. The system stillfurther includes a dilator operatively coupled to the elongated body ofthe first or second implant trial during use for distracting the discspace. The dilator is located in the longitudinal slot of the first orsecond implant trial. The system still further includes first and secondinsertion instruments including an elongated body and an insertionmember coupled to the elongated body. The elongated body of the firstinsertion instrument is slidable through the opening of the first guidemember and the elongated body of the second insertion instrument isslidable through the opening of the second guide member. The elongatedbodies of the first and second insertion instruments each include thesecond portion of the locking mechanism, such that, during use, when thefirst and second portions of the locking mechanism are engaged, thefirst and second guide members of the guide frame are fixedly coupled tothe respective elongated bodies of the first and second insertioninstruments at a selected location on the elongated bodies of the firstand second insertion instruments. The insertion members of the first andsecond insertion instruments are releasably coupled to respectivecomplementary interbody devices during use.

In some embodiments, provided is an apparatus for implanting aninterbody device into a disc space located between a first and secondvertebra including a guide frame, the guide frame including an insertionbridge and first and second guide members. The first and second guidemembers of the guide frame are rigidly coupled to the insertion bridgeand positioned at a convergent angle between about 20° to 30° relativeto one another during use. The first and second guide members of theguide frame each include openings receiving an elongated body duringuse, the openings including a channel with a lateral opening. The firstand second guide members of the guide frame each include at least afirst portion of a locking mechanism fixedly coupling the guide frame toan elongated body during use.

In some embodiments, provided is an apparatus for implanting aninterbody device into a disc space located between a first and secondvertebra including an implant trial, the implant trial including anelongated body. The implant trial further including a base plate coupledto the elongated body during use. The base plate includes an inferiorand/or superior surface having a shape that is substantially the same asthe shape of an inferior and/or superior surface of an interbody device.The implant trial still further including a dilator releasably coupledto the elongated body during use such that the dilator can be uncoupledfrom the elongated body and replaced with another dilator. The implanttrial still further includes a nerve root shield coupled to theelongated body during use. The nerve root shield includes a surface thatis shaped complementary to a surface of the first or second vertebra.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will become apparent to thoseskilled in the art with the benefit of the following detaileddescription and upon reference to the accompanying drawings in which:

FIG. 1 is a perspective view of two dynamic interbody devices positionedbetween vertebrae in accordance with one or more embodiments of thepresent technique;

FIG. 2 is a rear view of the two dynamic interbody devices in accordancewith one or more embodiments of the present technique;

FIG. 3 is a front view of a first member of a dynamic interbody devicein accordance with one or more embodiments of the present technique;

FIG. 4 is a side view of the first member of the dynamic interbodydevice in accordance with one or more embodiments of the presenttechnique;

FIG. 5 is a top view of the first member of the dynamic interbody devicein accordance with one or more embodiments of the present technique;

FIG. 6 is a front view of a second member of the dynamic interbodydevice in accordance with one or more embodiments of the presenttechnique;

FIG. 7 is a side view of the second member of the dynamic interbodydevice in accordance with one or more embodiments of the presenttechnique;

FIG. 8 is a top view of the second member of the dynamic interbodydevice in accordance with one or more embodiments of the presenttechnique;

FIG. 9 is a bottom view of the second member of the dynamic interbodydevice in accordance with one or more embodiments of the presenttechnique;

FIG. 10 is a perspective view of the second member of the dynamicinterbody device in accordance with one or more embodiments of thepresent technique;

FIG. 11 is a perspective view of the third member of the dynamicinterbody device in accordance with one or more embodiments of thepresent technique;

FIG. 12 is a perspective view of a posterior stabilization system inaccordance with one or more embodiments of the present technique;

FIG. 13 is a side view of a dynamic interbody device and a posteriorstabilization system coupled to vertebrae in accordance with one or moreembodiments of the present technique;

FIG. 14 is a front perspective view of an implant trial in accordancewith one or more embodiments of the present technique;

FIG. 15 is a rear perspective view of the implant trial in accordancewith one or more embodiments of the present technique;

FIG. 16 is a side view of a lower portion of the implant trial inaccordance with one or more embodiments of the present technique;

FIG. 17 is a perspective view of the implant trial including a dilatorin accordance with one or more embodiments of the present technique;

FIG. 18 is a side view of a lower portion of the implant trial includinga dilator in accordance with one or more embodiments of the presenttechnique;

FIG. 19 is a perspective view of a guide frame in accordance with one ormore embodiments of the present technique;

FIG. 20 is a top view of a guide member of the guide frame with a guiderelease in a first position in accordance with one or more embodimentsof the present technique;

FIG. 21 is a top view of the guide member of the guide frame with aguide release in a second position in accordance with one or moreembodiments of the present technique;

FIG. 22 is a perspective view of an insertion instrument in accordancewith one or more embodiments of the present technique;

FIG. 23 is a perspective view of an implant trial having a base plateinserted into a disc space between vertebrae in accordance with one ormore embodiments of the present technique;

FIG. 24 is a front view of a lower portion of the implant trial of FIG.23 with the base plate inserted into a disc space between vertebrae inaccordance with one or more embodiments of the present technique;

FIG. 25 is a perspective view of an upper portion of the implant trialof FIG. 23 depicting a dilator being coupled to the implant trial inaccordance with one or more embodiments of the present technique;

FIG. 26 is a side view of a lower portion of the implant trial of FIG.23 having a base plate inserted into a disc space between vertebrae andincluding a dilator in accordance with one or more embodiments of thepresent technique;

FIG. 27 is a perspective view of an upper portion of the implant trialof FIG. 23 depicting a guide member being coupled to the implant trialin accordance with one or more embodiments of the present technique;

FIG. 28 is a perspective view of a second implant trial being coupled toa second guide member in accordance with one or more embodiments of thepresent technique;

FIG. 29 is a front view of lower portions of the two implant trialshaving respective base plates inserted into a disc space betweenvertebrae in accordance with one or more embodiments of the presenttechnique;

FIG. 30 is a perspective view of an upper portion of the implant trialof FIG. 23 including a drill guide in accordance with one or moreembodiments of the present technique;

FIG. 31 is a perspective view of an upper portion of the implant trialof FIG. 23 depicting a anchor guide being inserted into the disc spacein accordance with one or more embodiments of the present technique;

FIG. 32 is a side view of a lower portion of the implant trial of FIG.23 having a base plate inserted into a disc space between vertebrae andincluding drill and anchor guides in accordance with one or moreembodiments of the present technique;

FIG. 33 is a perspective view of the implant trial of FIG. 23 includingdrill and anchor guides having a base plate inserted into a disc spacebetween vertebrae and coupled to a guide member in accordance with oneor more embodiments of the present technique;

FIG. 34 is a perspective view of a top portion of an insertioninstrument being coupled to a guide member in accordance with one ormore embodiments of the present technique;

FIG. 35 is a side view of lower portion of the insertion instrument ofFIG. 34 coupled to a dynamic interbody device inserted into a disc spacebetween vertebrae in accordance with one or more embodiments of thepresent technique;

FIG. 36 is a front view of two insertion instruments coupled torespective dynamic interbody devices inserted into a disc space betweenvertebrae in accordance with one or more embodiments of the presenttechnique;

FIG. 37 is a flowchart that illustrates a method of inserting a dynamicinterbody device into a disc space in accordance with one or moreembodiments of the present technique.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Thedrawings may not be to scale. It should be understood, however, that thedrawings and detailed description thereto are not intended to limit theinvention to the particular form disclosed, but to the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the present invention as definedby the appended claims.

DETAILED DESCRIPTION

A “functional spinal unit” generally refers to a motion segment of aspine. The functional spinal unit may include two vertebrae, anintervertebral disc between the vertebrae, and the two facet jointsbetween the vertebrae. An “artificial functional spinal unit” refers toa functional spinal unit where one or more of the components of thefunctional spinal unit are replaced by implants or devices that permitat least some motion of the spine. At least a portion of theintervertebral disc and/or one or both of the facet joints may bereplaced by implants or devices during a spinal stabilization procedure.

As used herein, “coupled” includes a direct or indirect joining ortouching unless expressly stated otherwise. For example, a first memberis coupled to a second member if the first member contacts the secondmember, or if a third member is positioned between the first member andthe second member.

An “interbody device” generally refers to an artificial intervertebralimplant. The interbody device may replace a portion or all of anintervertebral disc. In some embodiments, a pair of interbody devices isinstalled during a spinal stabilization procedure. In some embodiments,one or more interbody devices are installed using a posterior approach.In other embodiments, one or more interbody devices may be installedusing an anterior approach or other type of approach. In someembodiments, one or more interbody devices are placed in a disc spacebetween vertebrae, and at least one posterior stabilization system iscoupled to the vertebrae. In some embodiments, one or more interbodydevices are placed in the disc space without coupling a posteriorstabilization system to the vertebrae.

A “fusion interbody device” generally refers to an interbody device thatfacilitates fusion of adjacent vertebrae coupled to the device. A fusiondevice may provide stabilization of adjacent vertebra to at leastpartially inhibit movement of the vertebra to facilitate bone growth tofuse the adjacent vertebra.

A “dynamic interbody device” generally refers to an interbody devicethat allows for flexion/extension, lateral bending and/or axial rotationof vertebrae coupled to the device.

In some embodiments, the dynamic interbody device is a bimodal device.Bimodal refers to a device that has at least two separate curvedsurfaces to accommodate flexion/extension with lateral bending and/oraxial rotation.

Dynamic interbody devices may have surfaces that contact vertebrae. Insome embodiments, a surface of the dynamic interbody device thatcontacts a vertebra may include one or more anchors, protrusions, and/orosteoconductive/osteoinductive layers or coatings. A anchor of thedynamic interbody device may be positioned in an aperture formed in avertebra. The aperture may be formed in the vertebra so that the dynamicinterbody device will be positioned at a desired location when insertedinto the patient.

In some embodiments, one or more dynamic interbody devices are installedin a disc space formed between vertebrae during a spinal stabilizationprocedure. The shape and/or size of a dynamic interbody device maydepend on a number of factors including surgical approach employed forinsertion, intended position in the spine (e.g., cervical or lumbar),and patient anatomy. As described in U.S. Patent Publication No.2009/0105829 to Gimbel et al., several sizes of interbody devices may beprovided in the instrument kit for the spinal stabilization procedure.The dynamic interbody devices may include indicia indicating the heightof the spinal stabilization devices.

The dynamic interbody devices may allow for flexion/extension, axialrotation, and/or lateral bending of vertebrae coupled to the dynamicinterbody device.

The dynamic interbody device may allow for coupled lateral bending andaxial rotation so that axial rotation causes some lateral bending andlateral bending causes some axial rotation. The dynamic interbody devicemay be formed so that a set amount of lateral bending results in a setamount of axial rotation.

In some embodiments, a pair of dynamic interbody devices may beinstalled between two vertebrae to establish all or a portion of aspinal stabilization system. Each dynamic interbody device of the pairof dynamic interbody devices may be installed using a posteriorapproach.

As used herein a “dynamic posterior stabilization system” generallyrefers to an apparatus that may be used to at least partially replace orsupplement a facet joint while allowing for both dynamic resistance andat least some motion of the first vertebra to be stabilized relative tothe second vertebra to be stabilized. The first vertebra and the secondvertebra may be vertebrae of a functional spinal unit. In someembodiments, bone fasteners of the dynamic posterior stabilizationsystem are secured to the first vertebra and the second vertebra. Insome embodiments, a bone fastener of the dynamic posterior stabilizationsystem may be coupled to a vertebra adjacent to the vertebrae of thefunctional spinal unit being stabilized. The bone fasteners may becoupled to lamina, pedicles, and/or vertebral bodies of the vertebrae.In some embodiments, dynamic posterior stabilization systems may bepositioned in three or more vertebrae to form a multi-levelstabilization system.

The dynamic posterior stabilization system may replace or supplement anormal, damaged, deteriorated, defective or removed facet joint. Thedynamic posterior stabilization system may include bone fasteners, anelongated member, and at least one bias member. The bias member mayprovide little or no initial resistance to movement of a first vertebracoupled to the system relative to a second vertebra coupled to thesystem. Resistance to additional movement of the first vertebra relativeto the second vertebra may increase. The increasing resistance providedby the bias member may mimic the behavior of a normal functional spinalunit. The dynamic posterior stabilization system may stabilize thevertebrae, limit the range of motion of the first vertebra relative tothe second vertebra, and/or share a portion of the load applied to thevertebrae. The dynamic posterior stabilization system may work inconjunction with one or more interbody devices to provide supportprovided by a natural facet. For example, a dynamic interbody device mayprovide for coupled lateral bending and axial rotation of the adjacentvertebra as well as enable flexion and extension, while the posteriorstabilization system provides for controlled/dampened lateral bending,axial rotation, flexion and extension of the adjacent vertebra.

In some embodiments, dynamic interbody devices and dynamic posteriorstabilization systems may be made of non-magnetic, radiolucent materialsto allow unrestricted intra-operative and post-operative imaging.Certain material may interfere with x-ray and/or magnetic imaging.Magnetic materials may interfere with magnetic imaging techniques. Mostnon-magnetic stainless steels and cobalt chrome contain enough ironand/or nickel so that both magnetic imaging and x-ray imaging techniquesare adversely affected. Other materials, such as titanium and sometitanium alloys, are substantially iron free. Such materials may be usedwhen magnetic imaging techniques are to be used, but such materials areoften radio-opaque and sub-optimal for x-ray imagining techniques. Manyceramics and polymers are radiolucent and may be used with both magneticimaging techniques and x-ray imaging techniques. The dynamic interbodydevices and/or the dynamic posterior stabilization systems may includecoatings and/or markers that indicate the positions of the devicesand/or systems during operative and/or post-operative imaging.

In some embodiments, two cooperative interbody devices (e.g., fusion ordynamic interbody devices) may be positioned in a disc space between twovertebrae during a spinal stabilization procedure. FIG. 1 is aperspective view of two interbody devices 100′, 100″ positioned betweenvertebrae 102, 104 in accordance with one or more embodiments of thepresent technique. In the illustrated embodiment, interbody devices100′, 100″ includes dynamic interboyde devices. Dynamic interbodydevices 100′, 100″ may be implanted using a posterior approach. Anteriorends and/or posterior ends of dynamic interbody devices 100′, 100″ maybe positioned near the edge of the endplates of vertebrae 102, 104 sothat the dynamic interbody devices abut strong, supportive bone of thevertebrae to be stabilized. Dynamic interbody devices 100′, 100″ may bebilateral devices with coupled axial rotation and lateral bending.Although several embodiments are discussed with regard to dynamicinterbody devices, the same or similar techniques may be employed forinserting other types of implants, such as fusion interbody devices(e.g, spinal fusion implants). For example, interbody devices 100′ and100″ may include fusion interbody devices in place of dynamic interbodydevices described herein.

FIG. 2 is a rear view of dynamic interbody devices 100′, 100″ inaccordance with one or more embodiments of the present technique. Eachdynamic interbody device 100′ or 100″ may include first member 106,second member 108 and third member 110. First members 106 may be coupledto second members 108 so that dynamic interbody devices 100′, 100″accommodate lateral bending and axial rotation of vertebrae coupled tothe dynamic interbody devices. In some embodiments, dynamic interbodydevices 100′, 100″ couple lateral bending and axial motion together sothat lateral bending motion causes axial rotation, and axial rotationcauses lateral bending. Third members 110 may be coupled to secondmembers 108 so that dynamic interbody device 100′, 100″ accommodateflexion and extension of vertebrae coupled to the dynamic interbodydevice. Dynamic interbody devices 100′, 100″ are shown in positions ofneutral lateral bending, neutral axial rotation and maximum flexion inFIG. 2. In some embodiments, the first members are coupled to the secondmembers to allow for lateral bending without coupled axial rotationand/or axial rotation without coupled lateral bending.

In some embodiments, first member 106 of dynamic interbody device 100′may be substantially a mirror image first member 106 of dynamicinterbody device 100″, and third member 110 of dynamic interbody device100′ may be substantially a mirror image of third member 110 of dynamicinterbody device 100″. In other embodiments, the first member of dynamicinterbody device 100′ may have a shape that is different than the mirrorimage of the first member of dynamic interbody device 100″ and/or thethird member of dynamic interbody device 100′ may have a shape that isdifferent than the mirror image of the third member of dynamic interbodydevice 100″.

Second member 108 of dynamic interbody device 100′ may be substantiallythe mirror image of second member 108 of dynamic interbody device 100″with the exception of second member 108 of dynamic interbody device 100′having portion 112 (e.g., a protrusion) that engages a complementaryportion 114 (e.g., a recess) of second member 108 of dynamic interbodydevice 100″ to join dynamic interbody device 100′ to dynamic interbodydevice 100″ when the dynamic interbody devices are positioned betweenvertebrae. In other embodiments, first member 106 of dynamic interbodydevice 100′ has a portion (e.g., a protrusion) that engages a portion(e.g., a recess) of first member 106 of dynamic interbody device 100″when the dynamic interbody devices are positioned between vertebrae. Inother embodiments, third member 110 of dynamic interbody device 100′ hasa portion (e.g., a protrusion) that engages a portion (e.g., a recess)of first member 110 of dynamic interbody device 100″ when the dynamicinterbody devices are positioned between vertebrae.

FIGS. 3-5 are front, side and top views, respectively, of first member106 of dynamic interbody device 100′ in accordance with one or moreembodiments of the present technique. First member 106 may includeanchor 116 (e.g., a keel or the like), superior surface 118, slot 120,and opening 122. Anchor 116 may reside in an aperture or recess formedin a vertebra when dynamic interbody device 100′ is positioned in a discspace between vertebrae. Anchor 116 may inhibit undesired movement ofdynamic interbody device 100′ relative to the vertebrae. Superiorsurface 118 of first member 106 may be curved. The curvature of superiorsurface 118 may complement a curvature of an inferior surface of thesecond member of the dynamic interbody device to allow the dynamicinterbody device to accommodate lateral bending.

First member 106 may include arcuate slot 120. Arcuate slot 120 mayinteract with a complementary protrusion of second member 108 to allowthe dynamic interbody device to accommodate axial rotation. Thecurvature of superior surface 118 and arcuate slot 120 allows dynamicinterbody device 100′ to provide coupled lateral bending and axialrotation to the vertebrae adjacent to the dynamic interbody device. Insome embodiments, second member 108 may have an arcuate slot and firstmember 106 may have a complementary protrusion.

Arcuate slot 120 and the protrusion of second member 108 may bedovetailed or include another type of interconnection system thatinhibits non-rotational separation of first member 106 from secondmember 108 when the protrusion of the second member is engaged in slot120 of the first member. End surfaces 124 of arcuate slot 120 mayinteract with the end surfaces of the protrusion of second member 108 toresist shear load applied to dynamic interbody device 100′ when thedynamic interbody device is positioned between vertebrae. End surfaces124 and the end surfaces of the protrusion of second member 108 may beguides for lateral bending and axial rotation of the vertebrae coupledto dynamic interbody device 100′.

First member 106 may include opening 122 in slot 120. A pin may bepositioned in opening 122. The pin may reside in a groove in secondmember 108 to define the maximum amount of lateral bending/axialrotation allowed by dynamic interbody device 100′. In other embodiments,a pin positioned in an opening in second member 108 may reside in agroove in first member 106 to define the maximum amount of lateralbending/axial rotation allowed by dynamic interbody device 100′.

FIGS. 6-10 are front, side, top, bottom and perspective views,respectively of second member 108 of dynamic interbody device 100′ inaccordance with one or more embodiments of the present technique. Secondmember 108 may include inferior surface 126, recessed surface 128,superior surface 130, protrusion 132, bearing 134, tabs 136, groove 138,and portion 112. Some of inferior surface 126 may rest on superiorsurface 118 of first member 106 when protrusion 132 is placed in thearcuate slot 120 of the first member. Inferior surface 126 may include acurvature that complements the curvature of superior surface 118 offirst member 106 and protrusion 132 may complement the arcuate slot inthe first member so that dynamic interbody device 100′ is able toaccommodate coupled lateral bending and axial rotation of the vertebrajoined to the dynamic interbody device.

Portion 112 of second member 108 of dynamic interbody device 100′ (shownin FIGS. 1 and 6) may engage a complementary portion of second member108 of second dynamic interbody device 100″ positioned adjacent todynamic interbody device 100′ when dynamic interbody devices 100′, 100″are positioned in a disc space between vertebrae. FIG. 10 depicts secondmember 108 with portion 114 that complements portion 112 of secondmember shown in FIG. 6. Engaging portion 112 of dynamic interbody device100′ with complementary portion 114 of dynamic interbody device 100″ maystabilize and align the dynamic interbody devices when the dynamicinterbody devices are positioned between vertebrae. Coupling andaligning dynamic interbody devices 100′, 100″ together with portions112, 114 may assure that the second members of the dynamic interbodydevices move in tandem relative to the first members of the dynamicinterbody devices.

Coupling dynamic interbody devices 100′, 100″ together with portions112, 114 may inhibit migration of the dynamic interbody devices and/orsubsidence of the vertebrae coupled to the dynamic interbody devices.Having complementary portions may require that a specific dynamicinterbody device be installed prior to the other dynamic interbodydevice during an insertion procedure. For example, the dynamic interbodydevice with a female connection portion (i.e., portion 114 in FIG. 10)may need to be installed first. After insertion, migration and/orremoval of the dynamic interbody devices is only possible by reversingthe insertion order with the two dynamic interbody devices held in thesame position as during insertion (i.e., neutral in axial rotation andlateral bending while in full flexion). Proper positioning of the twodynamic interbody devices may be determined by examining the position ofthe connected portions using imaging techniques before removal of theinsertion instruments.

As shown in FIG. 7, second member 108 may include bearing 134. Bearing134 may fit in a recess of third member 110 to allow the dynamicinterbody device to accommodate flexion and extension of the vertebracoupled to the dynamic interbody device. Bearing 134 may include tabs136. Tabs 136 may fit in tracks in third member 110 to inhibitseparation of second member 108 from the third member. To assemble thedynamic interbody device, third member 110 may be coupled to secondmember 108, and/or second member 108 may be coupled to first member 106.The first member will inhibit separation of the third member from thesecond member even when the dynamic interbody device is subjected to themaximum amount of extension.

As shown in FIG. 9, groove 138 may be formed in protrusion 132 of secondmember 108. In some embodiments, groove 138 may be open at one side ofsecond member 108. A pin in opening 112 of first member 106 may residein groove 138 of the assembled dynamic interbody device.

Second member 108 may include recessed surface 128 in inferior surface126. Recessed surface 128 may allow a portion of second member 108 toextend over a portion of first member 106 of second dynamic interbodydevice 100″ without interference during lateral bending.

FIG. 11 is a perspective view of third member 110 of dynamic interbodydevice 100′ in accordance with one or more embodiments of the presenttechnique. Third member 110 may include recess 140 with tracks 142.Recess 140 and tracks 142 may complement the bearing and tabs of thesecond member.

As shown in FIG. 2, first member 106 of each dynamic interbody device100′, 100″ may include opening 144. Opening 144 may accept acomplementary portion of another device. Opening 144 may be a threadedopening or have another type of releasable coupling mechanism. Opening144 may be used to releasably couple dynamic interbody device 100′ or100″ to an insertion instrument used for placing dynamic interbodydevice within an intervertebral disc space. In other embodiments,openings for the insertion instrument may be located in second member108 and/or the third member 110.

The dynamic interbody device may include one or more features that allowthe insertion instrument to hold the dynamic interbody device in adesired position. For example, first member 106 may include slot 146 andthird member 110 may include slot 148. In some embodiments, slots 146,148 may include other types of depressions such as a round hole orelongated slot for accepting a complementary portion of insertioninstrumentation. A portion of the insertion instrument may be placed inslots 146, 148. The portion of the insertion instrument that fits inslots 146, 148 may place the dynamic interbody device in a desiredposition for insertion between vertebrae (i.e., neutral axial rotation,neutral lateral bending, and full flexion). For example, a pin of aninsertion instrumentation placed in both of slots 148 and 146 may fixrelative rotational/bending/flexion positions of first member 106,second member 108 and/or third member 110 such that they may be held ina relatively fixed position during insertion into the intervertebraldisc space.

Dynamic interbody devices 100′, 100″ may work in conjunction to allowfor coupled lateral bending and axial rotation and/or flexion/extensionof vertebrae 102, 104 the dynamic interbody devices are positionedbetween. During an insertion procedure, careful positioning of thedynamic interbody devices 100′, 100″ may be needed to ensure thatdynamic interbody device 100′ works in conjunction with dynamicinterbody device 100″. In some dynamic interbody device embodiments, aseparation angle of about 30° (i.e., each implant oriented at about 15°from a center line (See angle 450 of FIG. 24) of endplate of theinferior vertebra being stabilized) is desired between dynamic interbodydevices 100′, 100″. In some dynamic interbody device embodiments, aseparation angle of about 24° (i.e., each implant oriented at about 12°from a center line (See angle 450 of FIG. 24) of endplate of theinferior vertebra being stabilized) is desired between dynamic interbodydevices 100′, 100″. Other embodiments of dynamic interbody devices maybe designed to operate in conjunction with each other at otherseparation angles.

In some embodiments, insertion instruments may allow insertion ofdynamic interbody devices 100′, 100″ so that ends of the dynamicinterbody devices touch. Intra-operative imaging may be used to ensurethe proper positioning and alignment of the dynamic interbody devices.In some embodiments, a portion of dynamic interbody device 100′ mayengage a portion of dynamic interbody device 100″ to ensure properpositioning of the dynamic interbody devices 100′, 100″. For example, adovetailed portion of dynamic interbody device 100′ fits in acomplementary groove of dynamic interbody device 100″ when the dynamicinterbody devices are properly positioned. Engaging dynamic interbodydevices may inhibit migration of the dynamic interbody devices afterinsertion.

The superior surface of the dynamic interbody device may be coupled toan upper vertebra of the vertebrae to be stabilized. An inferior surfaceof the dynamic interbody device may be coupled to the inferior vertebraof the vertebrae to be stabilized. At least a portion the superiorsurface may be positioned near the edge of the endplate of the uppervertebra so that the dynamic interbody device abuts strong, supportivebone of the upper vertebra. At least a portion of the inferior surfacemay be positioned near the edge of the endplate of the inferior vertebraso that the dynamic interbody device abuts strong, supportive bone ofthe inferior vertebra.

Dynamic posterior stabilization systems may be used to support vertebraeand/or to provide resistance to motion of a first vertebra relative to asecond vertebra. FIG. 12 is a perspective view of a posteriorstabilization system 200 in accordance with one or more embodiments ofthe present technique. Posterior stabilization system 200 may be anin-line dynamic posterior stabilization system 200. Dynamic posteriorstabilization system 200 may include first bone fastener 202, secondbone fastener 204, and dampener system 206. Embodiments of a dynamicposterior stabilization system are further described in U.S. PatentPublication No. 2009/0105829 to Gimbel et al.

FIG. 13 is a side view of dynamic interbody device 100 and posteriorstabilization system 200 positioned between vertebrae 102, 104 inaccordance with one or more embodiments of the present technique.

Dynamic posterior stabilization system 200 may share a portion of theload applied to vertebrae 102, 104 while providing guidance andresistance to flexion/extension and/or lateral bending that is, or isapproximate to, the resistance provided by a normal functional spinalunit. Allowing for movement of the dynamic interbody device and formovement of the dynamic posterior stabilization system may inhibitdeterioration of adjacent functional spinal units.

Bridge 300 may be coupled to second bone fastener 204 of dynamicposterior stabilization system 200. Bridge 300 may inhibit undesiredmigration of dynamic interbody device 100 relative to vertebrae 102, 104while still allowing for flexion, extension, lateral bending, and/oraxial rotation of the vertebrae. Bridge 300 may couple dynamic interbodydevice 100 to dynamic posterior stabilization system 200. Bridge 300 maybe coupled to dynamic posterior stabilization system 200 at or near tosecond bone fastener 204. Coupling bridge 300 to dynamic posteriorstabilization system 200 at or near to second bone fastener 204 mayinhibit or eliminate contact of the bridge with neural structure exitingfrom between the vertebrae. In some embodiments, a bridge may not beprovided.

In some embodiments, a posterior approach may be used to install astabilization system for a patient. The stabilization system may replaceone or more parts of a functional spinal unit of the patient. Thestabilization system may include one or more dynamic interbody devices,and one or more dynamic posterior stabilization systems.

A discectomy may provide a disc space between two vertebrae in which oneor more interbody devices may be implanted. In some embodiments, after adiscectomy, two implant trials may be inserted into the disc spacebetween the vertebrae. The implant trials may facilitate properinsertion of one or more dynamic interbody devices into the disc space.For example, the implant trials may be used to properly align andposition the dynamic interbody devices within the disc space.Additionally, the implant trials may be used to separate or distract thevertebrae to allow insertion of the dynamic interbody devices into thedisc space. The implant trials may be inserted on opposite sides of thesagittal plane of the vertebrae. The implant trial used on one side ofthe sagittal plane may be a mirror image of the implant trial used onthe other side.

FIGS. 14-18 depict various views of an implant trial 400 in accordancewith one or more embodiments of the present technique. Implant trial 400may include elongated body 402, base plate 404, and nerve root shield406. Nerve root shield 406 may include elongated portion 406 a andshielding portion 406 b. During use, when the implant trial 400 isinserted into the disc space, shielding portion 406 b may be locatedsuperiorly to base plate 404. Nerve root shield 406 may abut portions ofthe vertebra during insertion. For example, shielding portion 406 b mayabout an end plate of the vertebrae and shielding portion 406 a maycontact a posterior edge portion of the vertebrae proximate the endplateas implant trial 400 is advanced into the intervertebral space adjacentthe vertebrae. Nerve root shield 406 may inhibit contact of otherportions (e.g., body 402) with the vertebrae.

Elongated body 402 may be any physical structure, having more lengththan width, capable of at least partially supporting another object.Additionally, elongated body 402 may have any suitable shape. Forexample, in the illustrated embodiment, elongated body 402 includes acombination of straight and curved surfaces. Elongated body 402 mayinclude key 408, slot 410, pin catch 412, channel/groove 414, andaperture 416. Key 408 may ensure that only a proper guide member can beused in association with the implant trial 400. For example, key 408 mayhave an external shape that is complementary to an internal shape of theproper (e.g., right or left) guide member. Slot 410 may be locatedbetween a portion of elongated body 402 and elongated portion 406 a ofnerve root shield 406. During use, a dilator may be inserted throughslot 410 (thereby coupling the dilator to the implant trial) to distractthe disc space. Pin catch 412 may form a portion of a locking mechanism.Pin catch 412 in conjunction with one or more other portions of thelocking mechanism may couple implant trial 400 to the guide member andfix the position of the implant trial relative to the guide member (andvice versa). For example, pin catch 412 may receive a complementarybiased stop pin of the proper guide member. Channel/groove 414 mayextend from the distal end of elongated body 402 to the proximal end ofelongated body 402. Channel/groove 414 may be substantially parallel toa longitudinal axis of body 402. A drill bit or other type of cuttingtool (e.g., an end mill, countersink, or reamer) may be inserted throughchannel/groove 414 to form an aperture in the inferior vertebra foraccommodating the anchor of a dynamic interbody device. Aperture 416 mayextend laterally through elongated body 402 when the implant trial 400is inserted into the disc space. In some embodiments, aperture 416 maybe perpendicular or oblique to a longitudinal axis of body 402. In someembodiments, a true lateral image of the implant trial 400 may beachieved by aligning imaging equipment with aperture 416.

Base plate 404 may be coupled to elongated body 402. Base plate 404 mayinclude inferior surface 404 a and superior surface 404 b. Inferiorsurface 404 a may have a shape that is substantially the same as theshape of an inferior surface of a dynamic interbody device (e.g.,inferior surface of first member 106 of dynamic interbody device 100′).Base plate 404 may further include x-ray visible features 418 and 420.The location of x-ray visible feature 418 within the disc space maycorrespond to the approximate location of the anterior edge of a dynamicinterbody device when the device is inserted into the disc space inplace of base plate 404. That is, x-ray visible feature 418 may indicatethe approximate expected location of the anterior edge of the dynamicinterbody device being inserted subsequent to positioning of implanttrial. For example, if base plate 404, coupled to elongated body 402, isremoved from the disc space and the dynamic interbody device, coupled tothe insertion member of an insertion instrument, is inserted into thedisc space via the same guide member as base plate 404, then theanterior edge of the dynamic interbody device may be located atapproximately the same anterior-posterior depth within the disc space aswas x-ray visible feature 418. Similarly, x-ray visible feature 420 mayindicate the approximate expected location of the center of rotation ofthe dynamic interbody device. Thus, advantageously, the dynamicinterbody device may be inserted between the vertebrae in properalignment by correctly positioning the x-ray visible features of baseplate 404 within the disc space. In some embodiments, implant trial 400may include one or more additional features that are visible viaintra-operative techniques (e.g., x-ray, computed tomography,ultrasound, and magnetic resonance imaging).

In some embodiments, one or more dilators 422 may be used to distractthe disc space. FIGS. 17 and 18 are perspective and side views,respectively, of implant trial 400 including dilator 422 in accordancewith one or more embodiments of the present technique. As depicted inFIGS. 17 and 18, one or more dilators 422 may be positioned between baseplate 404 and nerve root shield 406 to facilitate separation of thevertebrae. In some embodiments, with a leading end of insertioninstrument 400 disposed in a vertebral space between adjacent vertebra,insertion of dilator 422 may spread inferior and superior surfaces ofbase plate 404 and nerve root shield 406 apart, thereby engaging the endplates of the vertebrae and distracting the vertebrae apart from oneanother. Distraction may increase the distance between the two vertebrato facilitate subsequent insertion of one or more dynamic interbodydevices (e.g., dynamic interbody devices 100′ and 100″) within the discspace. For example, distraction may be conducted to a distance that isabout the same or greater than a height of the dynamic interbody deviceto be implanted. Dilator 422 may include proximal portion 422 a,elongated portion 422 b, and distal portion 422 c. Proximal portion 422a of dilator 422 may have an inferior and/or superior surface with ashape that is substantially the same as the shape of an inferior and/orsuperior surface of a dynamic interbody device. Dilator 422 may bereleasably coupled to elongated body 402 to distract the disc space. Forexample, in the illustrated embodiment, dilator 422 is inserted throughslot 410 of elongated body 402 such that the proximal portion 422 a ofthe dilator is located between an inferior/superior surface of baseplate 404 and a superior/interior surface of shielding portion 406 b ofnerve root shield 406. During use, dilator 422 may be uncoupled fromelongated body 402 and replaced with another dilator. For example,dilator 422 may be extracted from slot 410 of elongated body 402.Dilator 422 may include lip 424 and x-ray visible feature 426. Lip 424may limit insertion of dilator 422 through slot 410. For example, in theillustrated embodiment, lip 424 may be located proximate distal end 422c of dilator 422 and may engage a complementary portion of elongatedbody 402, thereby preventing over-insertion of dilator 422 between basepate 404 and shielding portion 406, and the disc space. X-ray visiblefeature 426 may indicate the approximate expected location of theposterior edge of the dynamic interbody device. In some embodiments,x-ray visible feature 426 is radio-opaque. In some embodiments, dilator422 may include one or more additional features that are visible viaintra-operative techniques (e.g., x-ray, computed tomography,ultrasound, and magnetic resonance imaging).

When dilator 422 is positioned in slot 410, shielding portion 406 b ofnerve root shield 406 may be pressed against the end plate of thesuperior vertebra. Shielding portion 406 b may protect the nerve root ofthe superior vertebra during the insertion of dilator 422. For example,shielding portion 406 b may inhibit chafing of the nerve root bypreventing direct contact between dilator 422 and the nerve root. Insome embodiments, a surface of shielding portion 406 b is shapedsubstantially complementary to a surface of the superior vertebra.Additionally, shielding portion 406 b may have a superior surface with ashape that is substantially the same as the shape of a superior surfaceof the dynamic interbody device to be inserted in its place.

A guide frame 428 may couple two implant trials to one another duringuse, thereby fixing the positions of the implant trials relative to oneanother during use. Fixing the implant trials relative to one anothermay help to ensure that the dynamic interbody devices are disposed indesired positions relative to one another. FIG. 19 is a perspective viewof guide frame 428 in accordance with one or more embodiments of thepresent technique. Guide frame 428 may include guide members 430, andinsertion bridge 432 coupling the guide members. Insertion bridge 432may include handle portion 432 a and coupling portion 432 b. Handleportion 432 a may provide for grasping and manipulation of guide frame428 by a user. Coupling portion 432 b may provide for coupling of guidemembers 430 and instrumentation thereto.

Guide members 430 may be coupled to insertion bridge 432 such that theguide members are positioned at a selected convergent angle relative toone another. In various embodiments, guide members 430 are rigidlycoupled to one another during use via coupling of each of guide members430 to portion 432 b of insertion bridge 432. In some embodiments, theconvergent angle is about 45° between longitudinal axes of the guidemembers, or about 22.5° from a midline axis of insertion bridge 432. Insome embodiments, the convergent angle is about 20° to 30° betweenlongitudinal axes of the guide members, or about 10° to 15° from amidline axis of insertion bridge 432. In certain embodiments, theconvergent angle is about 24° between longitudinal axes of the guidemembers, or about 12° from a midline axis of insertion bridge 432. Insome embodiments, the position of one guide member is substantiallymirrored by the other guide member. That is, the guide members areequally angled from a midline axis of insertion bridge 432.

Guide member 430 may include guide 434 and guide release 436. FIGS. 20and 21 are top views of guide member 430 with guide release 436 in afirst (locked) position and a second (unlocked) position, respectively,in accordance with one or more embodiments of the present technique. Theinternal shape of guide 434 may define an opening 434 a. Opening 434 amay be of any suitable shape or size. For example, in the illustratedembodiment, opening 434 a includes a channel having a lateral opening.In some embodiments, opening 434 a includes a laterally enclosed passagehaving a longitudinal opening. Opening 434 a may be complementary to theexternal shape of a key of the proper corresponding implant trial orinsertion instrument. As such, opening 434 a may guide longitudinalmovement of the implant trial or insertion instrument relative to guideframe 428. For example, the elongated body of an implant trial orinsertion instrument may slide longitudinally through opening 434 a ofguide 434.

Guide release 436 may include grip 438 and stop pin 440. Stop pin 440may form a portion of a locking mechanism. Stop pin 440 in conjunctionwith one or more other of the locking mechanism may couple implant trial400 to guide member 430 and fix the position of the implant trialrelative to guide member 430. For example, stop pin 440 may protrudeinto the complementary pin catch of an implant trial 400. In a first(locked) position (depicted in FIG. 20), stop pin 440 may extendlaterally into opening 434 a of guide 434. For example, a spring orother bias member (not shown) may urge stop pin 440 into opening 434 a.In a second (unlocked) position (depicted in FIG. 21), stop pin 440 maybe pulled out of opening 434 a via grip 438. With pin 440 in theunlocked position, implant trial 400 or similar instrumentation may beable to slide longitudinally though opening 434 a, whereas, with pin 440in the locked position, the implant trial 400 or similar instrumentationmay be inhibited from sliding longitudinally though opening 434 a

FIG. 22 is a perspective view of an insertion instrument 500 inaccordance with one or more embodiments of the present technique. Insome embodiments, two cooperative dynamic interbody devices may beinserted between the vertebrae using one or more insertion instruments500. For example, each of the dynamic interbody devices may bereleasably coupled to a respective insertion instrument. In someembodiments, subsequent to distraction of the intervertebral space viathe above described techniques, a first of the implant trials 400 isremoved from opening 434 a of guide frame 428 and replaced with a firstinsertion instrument 500 having a first dynamic interbody device coupledthereto, followed by a second of the implant trials 400 being removedfrom the other opening 434 a of guide frame 428 and replaced with asecond insertion instrument 500 having a second dynamic interbody devicecoupled thereto. In some embodiments, the insertion instrument for thesecond dynamic interbody device may be a mirror image of the insertioninstrument for the first dynamic interbody device.

Insertion instrument 500 may include elongated body 502, insertionmember 504, wheel 506, and insert(s) 507. Elongated body 502 may includekey 508, pin catch 510, passageway 512, and ridge/protrusion 514. Key508 may ensure that only the proper guide member can be used inassociation with the particular insertion instrument. For example, key508 may have an external shape that is complementary to the internalshape (e.g., shape of opening 434 a) of the proper guide member. In someembodiments, the proper guide member for the insertion instrument 500may be the same guide member used in conjunction with implant trial 400.For example, the external shape of key 508 of insertion instrument 500may be substantially the same as the external shape of key 408 ofimplant trial 400. Pin catch 510 may form a portion of a lockingmechanism. Pin catch 510 in conjunction with one or more other portionsof the locking mechanism may couple the insertion instrument to theguide member and fix the position of the insertion instrument relativeto the guide member. For example, pin catch 510 may receive acomplementary biased stop pin of the proper guide member. Insert 507 mayprovide for the adjustment of a height/thickness of insertion instrument500 to match a specific height implant. For example, the illustratedembodiment, insert 507 labeled “12 mm” is designed for use with a 12 mmimplant (e.g., interbody device 100′, 100″).

Insertion member 504 may be coupled to elongated body 502 of insertioninstrument 500. For example, in the illustrated embodiment, insertionmember 504 may be positioned within passageway 512 of elongated body502. In some embodiments, insertion member 504 is telescopically coupledto elongated body 502. For example, in the illustrated embodiment, wheel506 may be rotated to rotate insertion member 504. Rotating insertionmember 504 may advance or retract the insertion member relative to theelongated body 502 of insertion instrument 500.

In some embodiments, insertion member 504 is provided with asubstantially circular cross-section. For example, in the illustratedembodiment, insertion member 504 includes a cylindrical rod shapedmember. Insertion member 504 may include a distal end 504 a and aproximal end 504 b. Distal end 504 a of insertion member 504 may becoupled to wheel 506. Proximal end 504 b of insertion member 504 mayprotrude from the proximal end of elongated body 502. Proximal end 504 bof insertion member 504 may be threaded. An appropriate dynamicinterbody device may be releasably coupled to insertion member 504. Forexample, proximal end 504 b of insertion member 504 may mate with athreaded opening in the appropriate dynamic interbody device. Further,when proximal portion 504 b of insertion member 504 is threaded to theappropriate dynamic interbody device, ridge 514 may reside in acorresponding slot of the dynamic interbody device to place the dynamicinterbody device in the desired position for insertion (i.e., neutralaxial rotation, neutral lateral bending, and full flexion).

FIGS. 23-36 illustrate a sequence of steps for inserting a dynamicinterbody device into a disc space. FIG. 37 is a flowchart thatillustrates a method 600 of inserting a dynamic interbody device into adisc space in accordance with one or more embodiments of the presenttechnique. Although several embodiments are discussed with regard todynamic interbody devices, the same or similar techniques may beemployed for inserting other types of implants, such as spinal fusionimplants. For example, the illustrated method may also be used forinserting one or more non-dynamic interbody devices (e.g., a pair offusion interbody) into a disc space. Method 600 may generally includeinserting a base plate of an implant trial into an intervertebral discspace; inserting one or more dilators into the disc space to achievedistraction of the disc space; removing the base plate and dilators fromthe disc space; and inserting the interbody device into the disc spacein substantially the same position as the base plate.

In some embodiments, method 600 includes inserting a base plate of animplant trial into an intervertebral disc space, as depicted at block602. Initially, when a dilator is not coupled to the elongated body (seeFIG. 23), the implant trial may have a distraction height that is lessthan the separation height of the vertebrae, thereby allowing forinsertion of base plate 404′ into the disc space between vertebrae 104and vertebrae 102 (not depicted in FIG. 23 for clarity). The distractionheight may be measured as the distance between inferior surface 404 a′of base plate 404′ and the superior surface of shielding portion 406 b′of nerve root shield 406′. The separation height 480 may be measured asthe distance between the superior surface of inferior vertebra 104 andthe inferior surface of superior vertebra 102 (see FIG. 26).

Base plate 404′ of implant trial 400′ may be selectively inserted andpositioned at least partially within the disc space. For example, in theillustrated embodiment, base plate 404′ is positioned at a selectedanterior-posterior depth 444 (see FIG. 24). In some embodiments, baseplate 404′ may be inserted into the disc space until x-ray visiblefeature 418′ is positioned at a selected distance from the anterior edge104 a of inferior vertebra 104. In some embodiments, base plate 404′ maybe inserted into the disc space substantially through a region borderedby the vertebral endplates, dura, and exiting nerve root (not shown) ofthe vertebrae. Base plate 404′ may be positioned against the superiorsurface of inferior vertebra 104. Base plate 404′ may be positionedwithin the disc space at a selected angle 450 with respect to thesagittal plane 452. In some embodiments, the selected angle is betweenabout 10° to 14°. In certain embodiments, the selected angle is about12°. Base plate 404′ may be positioned within the disc space such that aportion of the base plate is on or near the sagittal plane. Positioningof base plate 404′ may be confirmed by locating x-ray visible features418′, 420′, and/or an additional feature of base plate 404′ viaintra-operative (e.g., x-ray, computed tomography, ultrasound, andmagnetic resonance imaging). In some embodiments, lateral imagingtechniques may be used to confirm that anterior-posterior depth of baseplate 404′. Intra-operative equipment may be aligned with aperture 416′of implant trail 400′ to obtain a true lateral image of the implanttrial within the disc space.

In some embodiments, method 600 includes inserting one or more dilatorsto the disc space to achieve distraction of the disc space, as depictedat block 604. Proximal portion 422 a′ of dilator 422′ may be insertedbetween the vertebrae to distract the disc space. For example, in theillustrated embodiment, dilator 422′ may be removably inserted into slot410′ of implant trial 400′ (see FIG. 25). Dilator 422′ may be insertedinto slot 410′ until lip 424′ is engaged with a portion of elongatedbody 402′. The height of dilator 422′ may be such that shielding portion406 b′ of nerve root shield 406′ is pressed against the inferior face ofsuperior vertebra 102 (see FIG. 26). X-ray visible feature 426′ may belocated less than about 5 millimeters (about 0.196 inches) from theposterior vertebral body edge 104 b of inferior vertebra 104. Theposition of dilator 422′ may be verified by locating x-ray visiblefeature 426′ and/or an additional feature of dilator 422′ viaintra-operative (e.g., x-ray, computed tomography, ultrasound, andmagnetic resonance imaging).

Guide member 430′ of guide frame 428 may be placed proximate implanttrial 400′. Guide member 430′ may be coupled to implant trial 400′. Forexample, in the illustrated embodiment, grip 438′ of guide release 436′may be pulled outwards to withdraw a stop pin from opening 434 a′ ofguide 434′; guide 434′ may then be engaged with key 408′ of elongatedbody 402′ (see FIG. 27). In some embodiments, guide 434′ is laterallyengaged with key 408′. In some embodiments, guide 434′ is longitudinallyengaged with key 408′. Grip 438′ may be released so that a spring inguide release 436′ urges the stop pin against key 408′. Once engaged,guide member 430′ may be lowered along key 408′ until the stop pinextends into pin catch 412′. In some embodiments, elongated body 402′ isslidable through opening 434 a′ of guide 434′.

Implant trial 400″ may be placed proximate second guide member 430″ ofguide frame 428 (see FIG. 28). Implant trial 400″ may be coupled toguide member 430″. For example, in the illustrated embodiment, grip 438″of guide release 436″ may be pulled outwards to withdraw a stop pin fromopening 434 a″ of guide 434″; key 408″ may then be engaged with guide434″. In some embodiments, key 408″ is laterally engaged with guide434″. In some embodiments, key 408″ is longitudinally engaged with guide434″. Grip 438″ may be released so that a spring in guide release 436″urges the stop pin against key 408″. Once engaged, implant trial 400″may be lowered along guide 434″ until the stop pin extends into pincatch 412″. In some embodiments, elongated body 402″ is slidable throughopening 434 a″ of guide 434″.

The position of base plate 404″ within the disc space may substantiallymirror the position of base plate 404′ within the disc space. As such, aportion of base plate 404″ may abut or be close to abutting the portionof base plate 404′ on or near the sagittal plane 452 (see FIG. 29).Angle 458 between the abutting portions of base plates 404′ and 404″ maybe equal to the convergent angle of the guide members. In someembodiments, angle 458 is about 20° to 30°. In certain embodiments,angle 458 is about 24°. In some embodiments, the base plates of theexpandable trials may be coupled together with male and female portionswhen the base plates are positioned between the vertebrae. In someembodiments, base plates 404′ and 404″ are positioned at a selected,substantially equal anterior-posterior depth 444. Positioning of baseplates 404′, 404″ may be confirmed via intra-operative (e.g., x-ray,computed tomography, ultrasound, and magnetic resonance imaging).

The proximal portion of a second dilator may be inserted between thevertebrae to further distract the disc space. For example, the seconddilator may be removably inserted into slot 410″ of implant trial 400″.The height of the second dilator may be such that shielding portion 406b″ of nerve root shield 406″ is firmly pressed against the inferior faceof superior vertebra 102. The dilators inserted into the disc space maybe sequentially removed and replaced one after the other withprogressively larger dilators until a maximum separation height isachieved. A maximum separation height may be achieved when the discspace opens posteriorly without parallel anterior separation. Theseparation height 480 between the vertebrae may be verified via lateralx-ray imaging. In some embodiments, the size of a dynamic interbodydevice to be implanted within the disc space is determined according tothe maximum separation height. In some embodiments, a height of theinterbody device is less than or equal to the maximum separation heightachieved via distraction. For example, the height of a dynamic interbodydevice may be about 2 millimeters (about 0.079 inches) or less than themaximum separation height achieved via distraction.

A drill guide 460′ may be positioned in a groove of implant trial 400′(see FIG. 30). Drill guide 460′ may include flag 462′ and tubular body464′. The proximal end of drill guide 460′ may abut the posteriorvertebral body edge 104 b of inferior vertebra 104. Flag 462′ may belocated at the distal end of the drill guide. The distance 466 betweenflag 462′ and a surface of elongated body 402′ may indicate theapproximate expected distance between the posterior end of the dynamicinterbody device and the posterior vertebral body edge 104 b of inferiorvertebra 104.

A anchor guide 468′ may be inserted through tubular body 464′ of drillguide 460′ to form an aperture in inferior vertebra 104 for the anchorof the dynamic interbody device (see FIG. 31). Anchor guide 468′ mayinclude shaft 470′, drill bit 472′, and drill stop 474′. Shaft 470′ mayextend drill bit 472′ through tubular body 464′ and into the disc space.Drill bit 472′ may pierce the vertebral body of the inferior vertebra104, thereby forming an aperture (see FIG. 32) in the inferior vertebra.Drill stop 474′, located near the distal end of the anchor guide, mayabut a portion of elongated body 402 to prevent boring of the vertebralbody passed a selected depth. Similar drill and anchor guides may beused in conjunction with implant trial 400″ to form a second aperture inthe vertebral body of the inferior vertebra 104.

In some embodiments, method 600 removing the base plate and dilatorsfrom the disc space, as depicted at block 606. A dilator may be removedfrom the disc space and slot 410″ to decrease the distraction height ofimplant trial 400″. Implant trial 400″ may be uncoupled from guidemember 430″ of guide frame 428. For example, in the illustratedembodiment, grip 438″ of guide release 436″ may be pulled outwards towithdraw the stop pin from guide 434″. Implant trial 400″ may then beremoved from the disc space and guide member 430″. Base plate 404″ ofimplant trial 400″ may be removed from the disc space while base plate404′ of implant trial 400′ remains at least partially inserted in thedisc space (see FIG. 33).

In some embodiments, method 600 includes inserting the interbody deviceinto the disc space in substantially the same position as the baseplate, as depicted at block 608. Insertion instrument 500″ coupled todynamic interbody device 100″ may be placed proximate guide member 430″of guide frame 428. Elongated body 502″ of insertion instrument 500″ maybe coupled to guide member 430″. For example, in the depictedembodiment, grip 438″ of guide release 436″ may be pulled outwards towithdraw the stop pin from the opening of guide 434″; key 508″ may beengaged with guide 434″ (see FIG. 34). In some embodiments, key 508″ islaterally engaged with guide 434″. In some embodiments, key 508″ islongitudinally engaged with guide 434″. Grip 438′ may then be releasedso that the spring in guide release 436″ urges the stop pin against key508″. Once engaged, insertion instrument 500″ may be lowered throughguide 434″ until the stop pin extends into pin catch 510″. Anchor 116 ofdynamic interbody device 100″ may be received by the aperture formed ininferior vertebra 104. If needed, a mallet or other impact instrumentmay be driven against a distal end of insertion instrument 500″ to drivedynamic interbody device 100″ between the vertebrae (see FIG. 35).

Implant trial 400′ may be removed from the disc space and guide member430′ of guide frame 428. Insertion instrument 500′ coupled to dynamicinterbody device 100′ may be inserted in a similar manner as thatdescribed above with respect to insertion instrument 500″ and dynamicinterbody device 100″. FIG. 36 depicts insertion instruments 500′, 500″and dynamic interbody devices 100′, 100″ positioned in the disc space.Positioning of dynamic interbody devices 100′, 100″ may be confirmed viaintra-operative (e.g., x-ray, computed tomography, ultrasound, andmagnetic resonance imaging). In some embodiments, when the dynamicinterbody devices 100′, 100″ are properly interconnected and positioned,insertion members 504′, 504″ may be uncoupled from the respectiveportions of the dynamic interbody devices 100′, 100″. For example, inthe illustrated embodiment, wheels 506′, 506″ of insertion instruments500′, 500″ may be rotated to withdraw insertion members 504′, 504″ fromopenings 144 of dynamic interbody devices 100′, 100″. Grips 438′, 438″of guide members 430′, 430″ may be pulled outwards to retract the stoppins of the guide releases 436′, 436″ from channels 434′, 434″, andinsertion instruments 500′, 500″ may be removed from the disc space andguide members. It will be appreciated that the above describedtechniques are illustrative, and modifications thereto may be within thescope of this disclosure. For example, in some embodiments, implanttrial 400′ may be removed and insertion instrument 500′ and dynamicinterbody device 100′ may be installed prior to removal of implant trial400″ and installation of insertion instrument 500″ and dynamic interbodydevice 100″. In some embodiments, insertion bridge 428 and/or guideframe 432 may be removed prior to removal of insertion instruments 500′,500″.

Additional techniques that may be used to insert dynamic interbodydevices between vertebrae are described in U.S. Patent Publication No.2009/0105829 to Gimbel et al.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the invention. It is to beunderstood that the forms of the invention shown and described hereinare to be taken as examples of embodiments. Elements and materials maybe substituted for those illustrated and described herein, parts andprocesses may be reversed, and certain features of the invention may beutilized independently, all as would be apparent to one skilled in theart after having the benefit of this description of the invention.Changes may be made in the elements described herein without departingfrom the spirit and scope of the invention as described in the followingclaims. Furthermore, note that the word “may” is used throughout thisapplication in a permissive sense (i.e., having the potential to, beingable to), not a mandatory sense (i.e., must). The term “include”, andderivations thereof, mean “including, but not limited to”. As usedthroughout this application, the singular forms “a”, “an” and “the”include plural referents unless the content clearly indicates otherwise.Thus, for example, reference to “a member” includes a combination of twoor more members. The term “coupled” means “directly or indirectlyconnected”.

In this patent, certain U.S. patents, and U.S. patent applications havebeen incorporated by reference. The text of such U.S. patents and U.S.patent applications is, however, only incorporated by reference to theextent that no conflict exists between such text and the otherstatements and drawings set forth herein. In the event of such conflict,then any such conflicting text in such incorporated by reference U.S.patents and U.S. patent applications is specifically not incorporated byreference in this patent.

What is claimed is:
 1. A method of implanting an interbody device into adisc space located between a first and second vertebra, comprising:inserting a base plate of a first implant trial into the disc space;inserting a base plate of a second implant trial into the disc space,wherein the second implant trial is coupled to the first implant trialto position the base plate of the first implant trial relative to thebase plate of the second implant trial; inserting one or more dilatorsinto the disc space proximate the base plates of the first or secondimplant trials to distract the first and second vertebrae; removing thebase plate of the first implant trial and the dilators from the discspace; and inserting the interbody device into the disc space insubstantially the same position as the base plate of the first implanttrial.
 2. The method of claim 1, wherein inserting a base plate of afirst implant trial into the disc space comprises inserting the baseplate to a selected location within the disc space, and wherein theselected location comprises a selected angle with respect to thesagittal plane of the vertebrae.
 3. The method of claim 1, wherein thefirst and second implant trials are coupled via a guide frame.
 4. Themethod of claim 3, wherein the guide frame comprises first and secondguide members and wherein the first implant trial is coupled to thefirst guide member and the second implant trial is coupled to the secondguide member.
 5. The method of claim 4, wherein the first and secondguide members comprise respective openings, and wherein inserting a baseplate of the second implant trial into the disc space compriseslongitudinal movement of the second implant trial through the opening ofthe second guide member.
 6. The method of claim 1, wherein at least oneof the implant trials comprises a nerve root shield, and whereininserting one or more dilators into the disc space comprises insertingthe dilators between the base plate and the nerve root shield.
 7. Themethod of claim 6, wherein the nerve root shield comprises a surfacethat is shaped complementary to a surface of the respective implanttrial.
 8. The method of claim 1, wherein inserting one or more dilatorsinto the disc space comprises inserting progressively larger dilatorsinto the disc space until the disc space opens posteriorly withoutparallel anterior separation.
 9. The method of claim 1, wherein thesecond implant trial is coupled to the first implant trial such that thebase plates of the first and second implant trials abut substantially ator near the sagittal plane of the vertebrae.
 10. A method of implantinginterbody devices into a disc space located between a first and secondvertebra, comprising: inserting a base plate of a first implant trial toa selected location at least partially within the disc space, the firstimplant trial comprising an elongated body and a base plate coupled tothe elongated body, wherein the selected location comprises a selectedangle with respect to the sagittal plane of the vertebrae; inserting afirst dilator between the base plate of the first implant trial and thefirst or second vertebra to distract the vertebrae; coupling a firstguide member of a guide frame to the elongated body of the first implanttrial, the guide frame further comprising a second guide member andwherein the first and second guide members of the guide frame arerigidly coupled and positioned at a selected convergent angle relativeto one another; coupling an elongated body of a second implant trial tothe second guide member such that a base plate of the second implanttrial is inserted at least partially within the disc space, and suchthat at least a portion of the base plate of the second implant trialabuts a portion of the base plate of the first implant trial; insertinga second dilator between the base plate of the second implant trial andthe endplate of the first or second vertebra to distract the vertebrae;removing the base plate of the first implant trial and the first dilatorfrom the disc space and uncoupling the elongated body of the firstimplant trial from the first guide member; coupling an elongated body ofa first insertion instrument to the first guide member such that a firstinterbody device is inserted at least partially within the disc space insubstantially the same position as the base plate of the first implanttrial, the first insertion instrument comprising the elongated body andan insertion member coupled to the elongated body, wherein the insertionmember is releasably coupled to the first interbody device, wherein thefirst interbody device is positioned within the disc space at a selectedangle with respect to the sagittal plane of the vertebra; removing thebase plate of the second implant trial and the second dilator from thedisc space and uncoupling the elongated body of the second implant trialfrom the second guide member; coupling an elongated body of a secondinsertion instrument to the second guide member such that a secondinterbody device is inserted at least partially within the disc space insubstantially the same position as the base plate of the second implanttrial, the second insertion instrument comprising an elongated body andan insertion member coupled to the elongated body, wherein the insertionmember is releasably coupled to the second interbody device, wherein atleast a portion of the second interbody device is located at or near thefirst interbody device; uncoupling the first interbody device from theinsertion member of the first insertion instrument; and uncoupling thesecond interbody device from the insertion member of the secondinsertion instrument.
 11. The method of claim 10, wherein the first andsecond implant trials and the first and second insertion instruments areat least partially inserted into the disc space substantially throughthe region bordered by the vertebral endplates of the first and secondvertebrae, dura, and exiting nerve root of the first and secondvertebrae.
 12. The method of claim 10, wherein the base plates of thefirst and second implant trials abut substantially at or near thesagittal plane of the vertebrae.
 13. The method of claim 10, wherein atleast one of the first and second implant trials comprises a nerve rootshield, and wherein inserting a first or second dilator comprisesinserting the dilator between the base plate and the nerve root shieldof the respective implant trial.
 14. The method of claim 13, wherein thenerve root shield comprises a surface that is shaped complementary to asurface of the first or second vertebra.
 15. The method of claim 10,wherein at least one of the dilators or one of the base plates of thefirst and second implant trials comprises an x-ray visible featureindicating an expected approximate location of a posterior edge of theinterbody device, and wherein the selected location further comprises aselected distance measured from the expected approximate location of theposterior edge of the interbody device to the posterior vertebral bodyedge of the first and/or second vertebra.
 16. The method of claim 10,wherein the base plates of the first and second implant trials eachcomprise an x-ray visible feature indicating an expected approximatelocation of a center of rotation of the interbody device, and whereinthe elongated body of a second implant trial is coupled to the secondguide member such that the x-ray visible features of the base plates ofthe first and second implant trials are located at a substantially equalanterior-posterior depth within the disc space.
 17. The method of claim10, wherein at least one of the base plates of the first and secondimplant trials comprises an x-ray visible feature indicating an expectedapproximate location of an anterior edge of the interbody device, andwherein the selected location further comprises a selected distancemeasured from the expected approximate location of the anterior edge ofthe interbody device to the anterior edge of the first and/or secondvertebra.
 18. The method of claim 10, wherein inserting a first orsecond dilator comprises inserting progressively larger dilators atleast partially into the disc space between the base plate of the firstand second implant trials respectively and the first or second vertebrauntil the disc space opens posteriorly without parallel anteriorseparation.
 19. The method of claim 18, wherein the disc height achievedat which the disc space opens posteriorly without parallel anteriordistraction is the maximum separation height of the disc space.
 20. Themethod of claim 19, wherein the height of the interbody device is lessthan the maximum achieved separation height of the disc space.
 21. Themethod of claim 10, wherein the elongated bodies are laterally engagedwith the respective guide members.